Leaf-Spring Oscillatory Actuator for Torsional Resonance Suppression

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Solution Overview

Problem

Conventional oscillatory actuators with movable magnets and leaf springs suffer from non-uniform magnetic fields and torsional resonance at frequencies other than natural resonance, leading to large oscillations and impaired haptic sensations.

Innovation Solution

An oscillatory actuator design featuring a cylindrical case with an electromagnetic driver, a mover oscillated by the driver, and leaf springs with elastic members bridging the arms, reducing torsional resonance and stabilizing natural resonance frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If weights are added to the mover to increase oscillation force, then oscillation output is improved, but torsional resonance occurs at frequencies other than natural resonance frequency due to non-uniform magnetic field and assembly variations

Engineering Contradiction:

Improveoscillation outputVSAvoidtorsional resonance

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

An elastic member is introduced as an intermediary component between the arms of the leaf spring. This elastic member acts as a mediator that reduces torsional stress and prevents torsional resonance while allowing the heavy mover to generate sufficient oscillation output. The elastic member bridges the gap between adjacent arms, providing flexibility that absorbs harmful torsional vibrations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The leaf spring structure is transformed into a composite system by combining rigid arms with a flexible elastic member. This composite structure maintains the strength needed to support the heavy mover while the elastic material properties of the bridging member provide torsional compliance, eliminating resonance issues at non-natural frequencies.

Inventive Principle:

Principle #40Composite materials

2Stability of the object's composition

If multiple leaf springs are used to support the mover, then structural stability is improved, but assembly variations cause non-uniform magnetic field leading to large oscillations at other frequencies

Engineering Contradiction:

Improvestructural stabilityVSAvoidoscillation frequency consistency

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The elastic member changes the mechanical parameters of the leaf spring system by introducing compliance to the arm connections. This parameter change allows the structure to accommodate assembly variations without transmitting them as harmful vibrations, maintaining both structural stability and frequency consistency.

Inventive Principle:

Principle #35Parameter changes

3Power

If the mover is made heavy to increase oscillation force, then natural resonance oscillation output is improved, but the system becomes more sensitive to torsional resonance from magnetic field non-uniformity

Engineering Contradiction:

Improveoscillation forceVSAvoidsensitivity to torsional resonance

Core Design Contradiction:

PowerVSObject-affected harmful factors

Solution Approach 1:

The elastic member serves as a protective intermediary that isolates the heavy mover from harmful torsional vibrations caused by magnetic field non-uniformity. This mediator allows the system to maintain high oscillation force while filtering out resonance disturbances.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The elastic members suppress torsional resonance, preventing large oscillations at frequencies other than natural resonance and ensuring sufficient oscillation outputs while minimizing changes in natural resonance frequencies.

Implementation Method 1

an electromagnetic driver provided inside the case; a mover oscillated by the electromagnetic driver

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

an elastic member which is made of an elastic material that bridges the arm and a portion adjacent to the arm with a gap

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS11831214B2Oscillatory actuator with leaf springs having elastic member bridging spring arms

Publication Date: 2023.11.28 FOSTER ELECTRIC CO LTD

AI summary

The disclosure provides an oscillatory actuator which includes a case in a cylindrical shape; an electromagnetic driver provided inside the case; a mover oscillated by the electromagnetic driver along an oscillation axis of the case; and a first leaf spring and a second leaf spring arranged on one side and the other side with the mover interposed therebetween, each of the first leaf spring and the second leaf spring including a support to which the mover is attached, an annular frame attached to an inner surface of the case, and a plurality of arms each having a spiral shape and connecting the support and the annular frame, wherein at least one of the first leaf spring and the second leaf spring is provided with an elastic member which is made of an elastic material that bridges the arm and a portion adjacent to the arm with a gap.